[PATCH 06/11] qdev: Add Error parameter to qdev_set_id()

[Kevin Wolf]

object_property_add_child() fails (with &error_abort) if an object with
the same name already exists. As long as QemuOpts is in use for -device
and device_add, it catches duplicate IDs before qdev_set_id() is even
called. However, for enabling non-QemuOpts code paths, we need to make
sure that the condition doesn't cause a crash, but fails gracefully.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 include/monitor/qdev.h      |  2 +-
 hw/xen/xen-legacy-backend.c |  3 ++-
 softmmu/qdev-monitor.c      | 16 ++++++++++------
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/include/monitor/qdev.h b/include/monitor/qdev.h
index 389287eb44..7961308c75 100644
--- a/include/monitor/qdev.h
+++ b/include/monitor/qdev.h
@@ -9,6 +9,6 @@ void qmp_device_add(QDict *qdict, QObject **ret_data, Error 
**errp);
 
 int qdev_device_help(QemuOpts *opts);
 DeviceState *qdev_device_add(QemuOpts *opts, Error **errp);
-void qdev_set_id(DeviceState *dev, char *id);
+void qdev_set_id(DeviceState *dev, char *id, Error **errp);
 
 #endif
diff --git a/hw/xen/xen-legacy-backend.c b/hw/xen/xen-legacy-backend.c
index dd8ae1452d..17aca85ddc 100644
--- a/hw/xen/xen-legacy-backend.c
+++ b/hw/xen/xen-legacy-backend.c
@@ -276,7 +276,8 @@ static struct XenLegacyDevice *xen_be_get_xendev(const char 
*type, int dom,
     xendev = g_malloc0(ops->size);
     object_initialize(&xendev->qdev, ops->size, TYPE_XENBACKEND);
     OBJECT(xendev)->free = g_free;
-    qdev_set_id(DEVICE(xendev), g_strdup_printf("xen-%s-%d", type, dev));
+    qdev_set_id(DEVICE(xendev), g_strdup_printf("xen-%s-%d", type, dev),
+                &error_abort);
     qdev_realize(DEVICE(xendev), xen_sysbus, &error_fatal);
     object_unref(OBJECT(xendev));
 
diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
index 1207e57a46..c2af906df0 100644
--- a/softmmu/qdev-monitor.c
+++ b/softmmu/qdev-monitor.c
@@ -593,26 +593,27 @@ static BusState *qbus_find(const char *path, Error **errp)
 }
 
 /* Takes ownership of @id, will be freed when deleting the device */
-void qdev_set_id(DeviceState *dev, char *id)
+void qdev_set_id(DeviceState *dev, char *id, Error **errp)
 {
     if (id) {
         dev->id = id;
     }
 
     if (dev->id) {
-        object_property_add_child(qdev_get_peripheral(), dev->id,
-                                  OBJECT(dev));
+        object_property_try_add_child(qdev_get_peripheral(), dev->id,
+                                      OBJECT(dev), errp);
     } else {
         static int anon_count;
         gchar *name = g_strdup_printf("device[%d]", anon_count++);
-        object_property_add_child(qdev_get_peripheral_anon(), name,
-                                  OBJECT(dev));
+        object_property_try_add_child(qdev_get_peripheral_anon(), name,
+                                      OBJECT(dev), errp);
         g_free(name);
     }
 }
 
 DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
 {
+    ERRP_GUARD();
     DeviceClass *dc;
     const char *driver, *path;
     DeviceState *dev = NULL;
@@ -691,7 +692,10 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
         }
     }
 
-    qdev_set_id(dev, g_strdup(qemu_opts_id(opts)));
+    qdev_set_id(dev, g_strdup(qemu_opts_id(opts)), errp);
+    if (*errp) {
+        goto err_del_dev;
+    }
 
     /* set properties */
     if (qemu_opt_foreach(opts, set_property, dev, errp)) {
-- 
2.31.1